The user @nkhorman made a very interesting measurement with a 2-channel oscilloscope showing the EG4-6500EX output while some LEDs are pulsing (different topic):This seems to be a classics case of an underdamped system. When the load is high, the PWM controller has to dump enough power into the pulse to not let the voltage drop, but when you drop the load near zero, it can't get the pulse width small enough to prevent overshoot. The number of inverters could also be an issue, since the latency between them has the effect of limiting the lower end of the PID controller bandwidth.
I'd have to bypass, and break the pairing to try... something I could do, but.... It's in operational use... didn't really want "go backward".Hard to tell just from looking at the waveform. Does it flicker when inverter is running alone and not paired with 2nd inverter? Problem could be related to paralleled mode of operation possibly due to synchronization data latency causing voltage overshoot.
176v?The user @nkhorman made a very interesting measurement with a 2-channel oscilloscope showing the EG4-6500EX output while some LEDs are pulsing (different topic):
EG4 6500EX Voltage/Frequency Fluctuations #1
EG4 6500EX Voltage/Frequency Fluctuations #2
Do you think this is the underdamped system behavior you describe to prevent overshoot, or is this something else?
What we call 120V AC is actually 170V at peak; the name "120V" is actually the "root mean square" (RMS) voltage. Long story short, a sine wave at 60Hz with voltage peaking at 170V (referred to as "Vp") is equivalent to 120V DC in terms of power dissipation, which is why it's called that.176v?